Photoradiation therapy, a technique which involves administration of hematoporphyrin derivative plus exposure to laser light, produces an inflammatory response in atherosclerotic rabbit aortas. The technique may thus have some application in the treatment of atherosclerotic cardiovascular disease. Preliminary studies are also underway to determine whether or not the technique may be useful for treatment of metaplasia and neoplasia in human breast tissue. Rapidly alternating magnetic fields appear to retard the growth of primary breast carcinoma in rats, and are being examined for their effects on other systems and tumor types.